The analysis of complex mixtures of biomolecules usually involves chromatographic or electrophoretic steps and are generally tedious, time-consuming and costly. Often, the analysis of complex mixtures has required combinations of selective extractions and chromatographic separations.
A widely used commercial analytical system for analysing complex mixtures of biomolecules is the PhastSystem™ (Amersham Pharmacia Biotech AB, Sweden) which is an analytical system based on electrophoresis on pre-prepared gels. While this system heavily facilitates the labour and time for the analytical operator, the system is still rather laborious and expensive.
U.S. Pat. No. 4,469,601 discloses a method and system for multi-dimensional chromatography in a thin-layer chromatographic plate wherein a sample is separated into an array of constituents. These constituents are then separated into a second array of sub-constituents by pumping a fluid through the plate in a direction crossing the array, and the sub-constituents are detected as they flow past fixed positions in this second direction. Thin layer chromatography is, however, restricted to the separation of small (i.e. low molecular weight) molecules, and does not permit the separation of biomolecules, such as proteins, for example.
Pristoupil, T. I., Chromatog. Rev., 12 (1970) 109-125 describes the use of nitrocellulose filters in chromatography and electrophoresis. Chromatography in aqueous solution was performed with a nitrocellulose membrane in a horizontal position in a plexiglass chamber. Proteins were detected by immersing the membrane in a staining solution, and other substances were detected by usual spray or sandwich techniques. On the intact membrane, proteins having a molecular weight of the order of 105 and higher were firmly adsorbed on the membrane while peptides, amino acids and other low-molecular substances of hydrophilic character migrated with the front of the developing solution. For electrophoresis, it was necessary to impregnate the membrane with neutral detergents to prevent the high adsorption of proteins. Also immunochromatography of rabbit anti-bovine serum and immunochemically inactive normal rabbit serum on a membrane with bovine serum adsorbed thereto is described. The antigen-antibody complex gave a distinct spot at the start, while the immunochemically inactive proteins migrated without any marked adsorption. Thus, no “true” chromatography of components seems to have been obtained neither in the intact (or plain) membrane nor in the antibody-coated membrane but rather either firm binding or no binding at all.